Integrated circuitry may comprise multiple levels of stacked wiring. The levels may include signal lines alternately arranged with shield lines. The shield lines may be utilized to alleviate cross-talk between adjacent signal lines. An example configuration comprising three stacked wiring levels is shown in FIG. 1. Specifically, the configuration shows a first level of wiring M1, a second level of wiring M2, and a third level of wiring M3; with M3 being over M2 which in turn is over M1. Although three wiring levels are shown, it is to be understood that there may be other wiring levels below the illustrated levels and/or above the illustrated levels. Also, although the illustrated wiring levels are labeled M1-M3, if other wiring levels are present the shown levels may in fact be M2-M4; M3-M6; etc., depending on the number of wiring levels present beneath the illustrated wiring levels.
Each of the illustrated levels comprises signal lines alternately arranged with shield lines. It may be desired for the shield lines within one level to be electrically connected with shield lines at other levels above and below said one level. For instance, it may be desired for the shield lines within level M2 to be electrically connected with shield lines within level M1 and shield lines within level M3, as such may alleviate coupling noises between the vertically-stacked levels.
Connection of shield lines from level M2 with those of level M1 is relatively straightforward since the lines within level M1 run perpendicular to the lines within level M2. However, the connection of shield lines from level M2 with those of level M3 is problematic since the wiring within level M2 runs parallel to that within level M3, and the shield lines are staggered in level M2 relative to level M3. Thus there is no vertical overlap between the shield lines of level M2 with those of level M3.
It would be desirable to develop architectures which enable coupling between shield lines of stacked levels of the type illustrated as levels M2 and M3 in FIG. 1.